1. Field of the Invention
The present invention relates to a thermosetting resin composition used for sealing an air gap formed between a printed circuit board and a semiconductor element in a semiconductor device. Further, the present invention relates to a semiconductor device manufactured by mounting a semiconductor element in a face-down structure on a printed circuit board using the resin composition.
2. Discussion of the Related Art
With the recent demand for performance improvement in the semiconductor devices, there has been proposed a method for mounting a semiconductor element in a face-down structure to a printed circuit board (flip-chip method, direct chip attachment method and the like). In the flip-chip method, since a semiconductor element and a printed circuit board, each having a different coefficient of thermal expansion, are directly electrically connected, there arise a problem in the reliability of the connecting parts. In view of this problem, there has been employed a method comprising filling a gap formed between the semiconductor element and the printed circuit board with a liquid resin material, and curing the liquid resin material to form a resin cured product, so that the stress concentrating in an electrically connected part is also distributed in the above-mentioned resin cured product, thereby improving connection reliability. The conventional method for filling a gap formed between the semiconductor element and the printed circuit board with a liquid material in the flip-chip method using a solder bump comprises firstly mounting the flip chip to a printed circuit board, forming metal bonding by a solder melting step, and thereafter injecting the liquid resin material in a gap formed between the semiconductor element and the printed circuit board. Since the method of filling the gap formed between the semiconductor element and the printed circuit board with the above-mentioned liquid resin material is carried out by the capillary tube effect of the liquid resin material, the viscosity of the liquid resin material must be adjusted to a low level. Therefore, there is a limited range of materials to select from in order to have a low viscosity, so that the uses of rubber components giving low-stress effects and a phenolic resin having high reliability have been difficult under these circumstances. Further, the above-mentioned liquid resin material must be stored at an ultralow temperature of about xe2x88x9240xc2x0 C. in order to stably keep the viscosity of the above-mentioned liquid resin material low, and the liquid resin material must be injected with a needle into a gap formed between the above-mentioned semiconductor element and board, so that there arise problems such as difficulty in the injection positioning or difficulty in controlling the amount of the injection.
In addition, since the method for manufacturing the above-mentioned semiconductor device comprises a large number of steps, low productivity becomes a problem. Further, in order to improve productivity as compared to that of the above-mentioned method, there has been proposed a pressing method comprising mounting a flip chip on a printed circuit board previously coated with a liquid material with applications of appropriate temperature and pressure. However, in the pressing method, an oxide layer must be removed during bump bonding in metal electrodes such as solder bumps requiring the formation of metal bond. Therefore, this method can only be applied to a process for manufacturing a semiconductor device which is subjected to electric connection by metal contact using, for instance, a gold stud bump, and it has been difficult to apply it to mounting of a semiconductor device having metal electrodes requiring the formation of metallic bonds such as solder bumps.
Further, in the recent year, a process for manufacturing a semiconductor device has been developed using a thermosetting resin material having a flux activity in an attempt for a more simplified process than the method of injecting a liquid material utilizing a capillary phenomenon, said process comprising previously applying the thermosetting resin material to a semiconductor element or a printed circuit board, carrying out resin sealing at the interface together with chip mounting, and forming metal bonding by solder reflow. Therefore, the production steps comprising application of flux and cleaning, and injection of a liquid resin and the like can be reduced, as compared to the conventional process for manufacturing a semiconductor device using a liquid resin material, so that the productivity of the semiconductor device can be improved. Since the method of filling the gap formed between the semiconductor element and the printed circuit board with the above-mentioned liquid resin material is carried out by a capillary tube effect of the liquid resin material, the viscosity of the liquid resin material must be adjusted to a low level. Therefore, since an acid anhydride-based curing agent is used for obtaining a low viscosity, the materials are selected from a limited range, so that it has been difficult to use a phenolic resin having high moisture tolerance reliability under these circumstances.
An object of the present invention is to provide a thermosetting resin composition having a flux activity, which has excellent relaxation effect of a stress caused between a semiconductor element or a printed circuit board and connecting electrodes, is capable of easily forming a sealing resin layer in an air gap formed between the semiconductor element and the printed circuit board, and does not need a cleaning step for the flux; and a semiconductor device manufactured by using the thermosetting resin composition. Also, another object of the present invention is to provide a thermosetting resin composition having excellent productivity, which enables mounting of flip chips to which a thermosetting composition having a function of removing a metal oxide layer or oxidation-preventing material (hereinafter referred to as pre-flux) existing on the surface of the electrodes on the semiconductor element or the printed circuit board in the process for manufacturing a semiconductor device requiring the formation of metal bonding such as solder bumps is previously applied; a semiconductor device manufactured by using the thermosetting resin composition; and a process for manufacturing the semiconductor device.
These and other objects of the present invention will be apparent from the following description.
According to the present invention, there are provided:
[1] a sheet-like thermosetting resin composition usable for sealing a gap formed between a printed circuit board and a semiconductor element in a semiconductor package having a face-down structure, comprising a compound having the general formula (1):
R1xe2x80x94(COOxe2x80x94CH(CH3)xe2x80x94Oxe2x80x94R2)nxe2x80x83xe2x80x83(1)
wherein n is a positive integer; R1 is a monovalent or higher polyvalent organic group; and R2 is a monovalent organic group, wherein R1 and R2 may be identical or different, or
a compound having the general formula (2):
CH2xe2x95x90CHxe2x80x94Oxe2x80x94R4xe2x80x94Oxe2x80x94CH(CH3)xe2x80x94[OCOxe2x80x94R3xe2x80x94COOxe2x80x94CH(CH3)xe2x80x94Oxe2x80x94R4xe2x80x94Oxe2x80x94CH(CH3)]nxe2x80x94OCOxe2x80x94R3xe2x80x94COOxe2x80x94CH(CH3)xe2x80x94Oxe2x80x94R4xe2x80x94Oxe2x80x94CHxe2x95x90CH2xe2x80x83xe2x80x83(2)
wherein n is a positive integer; each of R3 and R4 is a divalent organic group, wherein R3 and R4 may be identical or different;
[2] a thermosetting resin composition usable for sealing a gap formed between a printed circuit board and a semiconductor element in a semiconductor package having a face-down structure, comprising:
an epoxy resin,
a phenolic resin-based curing agent and
a compound having the general formula (1):
R1xe2x80x94(COOxe2x80x94CH(CH3)xe2x80x94Oxe2x80x94R2)nxe2x80x83xe2x80x83(1)
wherein n is a positive integer; R1 is a monovalent or higher polyvalent organic group; and R2 is a monovalent organic group, wherein R1 and R2 may be identical or different, or
a compound having the general formula (2):
CH2xe2x95x90CHxe2x80x94Oxe2x80x94R4xe2x80x94Oxe2x80x94CH(CH3)xe2x80x94[OCOxe2x80x94R3xe2x80x94COOxe2x80x94CH(CH3)xe2x80x94Oxe2x80x94R4xe2x80x94Oxe2x80x94CH(CH3)]nxe2x80x94OCOxe2x80x94R3xe2x80x94COOxe2x80x94CH(CH3)xe2x80x94Oxe2x80x94R4xe2x80x94Oxe2x80x94CHxe2x95x90CH2xe2x80x83xe2x80x83(2)
wherein n is a positive integer; each of R3 and R4 is a divalent organic group, wherein R3 and R4 may be identical or different;
[3] a process for manufacturing a semiconductor device comprising the steps of:
applying the thermosetting resin composition of item [2] above to a wafer, dicing the coated wafer into individual chips, and carrying out chip-mounting;
[4] a thermosetting resin composition comprising:
an epoxy resin,
an acid anhydride-based curing agent and
a compound having the general formula (1):
R1xe2x80x94COOxe2x80x94CH(CH3)xe2x80x94Oxe2x80x94R2)nxe2x80x83xe2x80x83(1)
wherein n is a positive integer; R1 is a monovalent or higher polyvalent organic group; and R2 is a monovalent organic group, wherein R1 and R2 may be identical or different, or
a compound having the general formula (2):
xe2x80x83CH2xe2x95x90CHxe2x80x94Oxe2x80x94R4xe2x80x94Oxe2x80x94CH(CH3)xe2x80x94[OCOxe2x80x94R3xe2x80x94COOxe2x80x94CH(CH3)xe2x80x94Oxe2x80x94R4xe2x80x94Oxe2x80x94CH(CH3)]nxe2x80x94OCOxe2x80x94R3xe2x80x94COOxe2x80x94CH(CH3)xe2x80x94Oxe2x80x94R4xe2x80x94Oxe2x80x94CHxe2x95x90CH2xe2x80x83xe2x80x83(2)
wherein n is a positive integer; each of R3 and R4 is a divalent organic group,
wherein R3 and R4 may be identical or different, and
wherein the thermosetting resin composition is liquid at 25xc2x0 C.;
[5] a thermosetting resin composition comprising:
(A) an epoxy resin having at least two epoxy groups in its molecule,
(B) a curing agent,
(C) a compound having the general formula (1):
R1xe2x80x94COOxe2x80x94CH(CH3)xe2x80x94Oxe2x80x94R2)nxe2x80x83xe2x80x83(1)
wherein n is a positive integer; R1 is a monovalent or higher polyvalent organic group; and R2 is a monovalent organic group, wherein R1 and R2 may be identical or different, or
a compound having the general formula (2):
CH2xe2x95x90CHxe2x80x94Oxe2x80x94R4xe2x80x94Oxe2x80x94CH(CH3)xe2x80x94[OCOxe2x80x94R3xe2x80x94COOxe2x80x94CH(CH3)xe2x80x94Oxe2x80x94R4xe2x80x94Oxe2x80x94CH(CH3)]nxe2x80x94OCOxe2x80x94R3xe2x80x94COOxe2x80x94CH(CH3)xe2x80x94Oxe2x80x94R4xe2x80x94Oxe2x80x94CHxe2x95x90CH2xe2x80x83xe2x80x83(2)
wherein n is a positive integer; each of R3 and R4 is a divalent organic group, wherein R3 and R4 may be identical or different; and
(D) a microcapsulated curing accelerator comprising a core portion comprising a curing accelerator, and a shell portion formed so as to cover the core portion, the shell portion comprising a polymer having a structural unit represented by a general formula (3):
xe2x80x94N(R5)xe2x80x94COxe2x80x94N(R6)xe2x80x94xe2x80x83xe2x80x83(3)
wherein each of R5 and R6 is hydrogen atom or a monovalent organic group, wherein R5 and R6 may be identical or different,
wherein the thermosetting resin composition has a reaction exothermic peak of 180xc2x0 to 250xc2x0 C. with a programming rate of 10xc2x0 C./min in the differential scanning calorimetric determination; and
[6] a semiconductor device comprising:
a printed circuit board,
a semiconductor element, and
the thermosetting resin composition of any one of items [1], [2], [4] and [5] above, wherein a gap formed between the printed circuit board and the semiconductor element is sealed by the thermosetting resin composition.